Examining the role of Golgi-associated protein, Lava lamp, in Drosophila development

The Golgi body is responsible for the modification and sorting of proteins and lipids in the secretory pathway. The Golgi must coordinate with other endomembrane compartments in order to target cargo to the correct destination. While our understanding of Golgi function is vast, we can extend our knowledge base by examining the functions of Golgi-associated proteins in developing animals. Lava lamp (Lva) is a Golgi-associated protein and a Drosophila golgin. Previously, Lva was shown to facilitate efficient membrane secretion required for cleavage furrow formation in early embryos. By acting as an adaptor molecule between Golgi and microtubule motility factors, Lva is thought to position Golgi bodies for targeted secretion during cellularization, the Drosophila cleavage stage of development. Here, I further characterize the role of Lva during animal development. I demonstrate that Lva is required for animal viability, and gamete production in females but not males. While Lva is expressed in many tissues, adult fat body cells are the most sensitive to decreased Lva activity, resulting in the disorganization of endomembrane compartments. Furthermore, this disruption in adult fat body cells correlates with a defect in neuroendocrine signaling, altering the activity of juvenile hormone. I propose that Lva activity in adult fat body cells is important for recognizing and/or processing juvenile hormone in order to support Drosophila oogenesis.
Lva’s role in cellularization, which is a specialized form of cytokinesis in early embryos, provided insights into the combined processes of actomyosin-based contraction and membrane secretion. While some proteins have been implicated in cellularization, there are thought to be many more that have yet to be identified. In an effort to isolate additional genes involved in animal cell cytokinesis, we screened a unique collection of temperature sensitive (ts) mutations on the X-chromosome of Drosophila melanogaster. At the restrictive temperature, we identified five mutants that displayed a cellularization phenotype. For one of the mutants, fs(1)ts242, we narrowed the mutation to a region on the X chromosome consisting of 17 possible gene candidates. Identification of the gene should provide further elucidation of the mechanisms controlling actomyosin-based contraction and membrane secretion.